OM is the Alpha and the Omega, the beginning and endings of all things. As MMY says in his translation/book "The Vedas",
"If you strike a bell it produces a hum-m-m-m. From that eternal silence a hum starts and this hum is called OM. You may have heard of the glory of OM and the greatness of OM, that OM is everything and that from OM the creation comes and into OM the creation dissolves, (the Alpha and the Omega) that OM is the sustain-er of life (Vishnu), that OM is the beginning (Brahma) and the end (Shiva) of ALL creation. All this is *OM*, that hum, which is the first silent sound, first silent wave that starts from that silent ocean of UN-manifested life. The Vedas, page two. (parenthesis added by poster) http://www.youtube.com/watch?v=NRMtVr-s9vo "Eko-ham bahu-ssyaam", "In the beginning was the Word and the Word was with God" (The word was OM).